The fluctuations in the growth of the thermophilic cyanobacterium Oscillatoria terebriformis population dynamics, environmental drivers, seasonal abundance, and the fluctuations in the expression of cellular proteins were recorded from sulfur water hot springs during high temperature environmental conditions. This study aimed to determine the effect of temperature on the growth of O. terebriformis. The growth curve of O. terebriformis was investigated on BG11 at the two different optimum temperatures (± 30 °C and ± 40 °C) to dissect the impact of the temperature change on growth. Furthermore, high temperature-induced cellular proteins were characterized and identified using SDS-PAGE technique and mass spectrometry analysis, respectively. At the eighth day of cultivation, O. terebriformis recorded high optical density in case of both studied temperatures. Concerning the expression of the cellular proteins, several polypeptides running at approximately 120, 85, 70, 50, 35, 30, and 20 kDa were significantly upregulated downstream of the high temperature stress conditions specifically at 70 °C. Induction of protein overexpression was detected in O. terebriformis samples incubated at 70 °C (as high temperature stress). Three unique polypeptides, running at approximately 35, 30, and 20 kDa were analyzed by nano HPLC–ESI–MS/MS mass spectrometry. The first and third polypeptides were identified as biopolymer transport inner membrane (Energy transduction protein D:ExbD) protein. The second polypeptide was identified as orotate phosphoribosyl transferase (OPRT) protein. The identified proteins are involved in iron transport/heat stress response and pyrimidine biosynthesis, respectively. The High temperature-induced proteins most likely contributed to thermotolerance cascades regulating the fluctuations in O. terebriformis during temperature changes, specifically at high temperature conditions. The impact of temperature stress on the expression pattern of some O. terebriformis proteins was studied to delineate the thermotolerance underpinning seasonal temperature changes. The results of this study may provide a better understanding of the cellular defense mechanisms against temperature stress in cyanobacteria, specifically thermophilic O. terebriformis.
Ali et al. (Mon,) studied this question.